Memorial Tributes: National Academy of Engineering, Volume 23
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  • Suzanne Kennedy
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  • REX A. ELDER 1917-2018


    REX ALFRED ELDER, formerly of TVA and Bechtel, passed away February 24, 2018, at the remarkable age of 100. He was a talented hydraulic engineer whose career spanned decades of the 20th century critical to the development of hydraulic engineering. When it came to the hydraulics of hydro-and thermal power systems, few (if any) engineers could match his perceptive, seasoned expertise, complemented by his down-to-earth manner.

    His professional activities focused on dams, coal and nuclear power plants, and resolution of concerns related to large pumps and other hydraulic machinery. He was particularly known for his work on stratified flows. Countlesshydraulic­ engineers became acquainted with his contributions, and many had the enriching experience of working with him.

    Rex was born October 4, 1917, the third child of George Alfred and Jane Elder, in the small town of Laquin in northern Pennsylvania (about 80 miles northwest of Scranton), where his father managed the local lumber mill. The community revolved around the regional lumber industry, which was struggling because of the declining availability of timber and then the economic impacts of the Great Depression.

    Rex’s pragmatic outlook developed early as he learned the lumber mill trades, riding draft horses that skidded logs to the mill and later driving lumber trucks. Although atypical for the early 20th century, his parents had each completed 2 years of college, and they encouraged their son’s university education. Rex attended Carnegie Institute of Technology (now Carnegie Mellon University) and in 1940 earned his bachelor’s degree in civil engineering. He then attended Oregon State College (now Oregon State University, OSU) where he obtained his master’s degree in hydraulic engineering in 1942.

    Degree in hand, he joined the Tennessee Valley Authority’s (TVA) Hydraulics Laboratory. By the end of World War II the TVA had completed a 1050 km navigation channel along the length of the Tennessee River and was the country’s largest electricity supplier. Rex’s career spanned TVA’s substantial growth as well as milestone advances in hydraulics theory, the use of hydraulics laboratories, associated instrumentation and modeling techniques, and methods for field investigation. The range of topics investigated played a critical role in the emergence of TVA’s Hydraulics Lab as the country’s leading nonuniversity hydraulics lab during the years that Rex served as its director (1948–61).

    At first, Rex was involved in a variety of technical activities engaging TVA’s Hydraulics Lab in Norris, Tennessee; in 1948 he became the lab’s director. In 1962 he was appointed director of TVA’s Engineering Laboratory, which investigated a broad range of engineering concerns. These promotions signaled both his talents as an engineer and his ability to collaborate with other professionals.

    During his 31 years at TVA (1942–73), the authority completed extensive studies for more than ten dams, a major pump storage facility, six navigation locks, and sundry other hydraulics facets of its expanding operation. Rex’s work on TVA’s hydropower dams extensively involved the design of spillways and inlet and outlet works.

    He was particularly proud of the spillway for the gravity-arch Fontana Dam on the Little Tennessee River in North Carolina. Built in 1942–44, the spillway involved a tunnel through rock forming an abutment of the dam and a flip bucket ejecting flow at the end of the tunnel. The project, and its site difficulties, spurred Rex’s expertise in cavitation, flow resistance in tunnels, and overall aspects of spillway design. His work with locks along the Tennessee River led to a novel approach for filling and draining navigation locks: the new design, a multiport manifold system, reduced lock filling time and lowered the cost of lock construction.

    In 1952 TVA started on a huge program of power generation by coal-fired thermal power plants, such that by 1955 coal sur-passed hydro as the authority’s main power source. Economic and environmental challenges began to emerge with wide-spread coal use, and energy demand was projected to keep expanding. Thus, in the mid-1960s TVA began to develop the use of nuclear reactors for generating electricity and in 1966 undertook the construction of Browns Ferry Nuclear Plant on the Tennessee River in Alabama. It was the authority’s first nuclear power plant and, at the time, one of few commercial nuclear power plants in the United States.

    TVA’s growth in the use of thermal power led Rex to conduct early studies of various aspects of the interdisciplinary field now known as environmental hydraulics. He and colleagues investigated the hydraulics of thermally stratified reservoirs and the design of water intakes to withdraw cooler water. They also conducted pioneering work on density currents and on the hydraulics of diffuser pipes for managing thermal effluent discharges. The efficient operation of Browns Ferry Nuclear Plant motivated some these studies.

    In 1973 Rex retired from TVA and joined Bechtel in San Francisco, where he expanded and managed the company’s Hydraulics and Hydrology Group, which supported the design of multiple projects. At the time Bechtel had projects with approximately 20 percent of the country’s new power-generating capacity and was extensively involved with overseas projects. Rex oversaw a sizable number of engineers and hydrologists in diverse projects associated with hydro-and thermal power plants as well as hydraulics issues related to large-scale mining and industrial facilities.

    Rex traveled extensively to solve hydraulic problems; his globe trotting took him to Algeria, Australia, Bolivia, Canada, Chile, Egypt, France, Japan, Saudi Arabia, South Korea, and Taiwan, among other places. In these projects he engaged with talented Bechtel engineers and a number of other ­hydraulics laboratories and experts, including those in academia. Throughout his career, he worked closely with hydraulics luminaries such as Donald Harleman (Massachusetts Institute of Technology), John F. Kennedy (University of Iowa), Norman Brooks (California Institute of Technology), Victor Streeter (University of Michigan), and Robert Dean (University of Florida), among others.

    He retired from Bechtel in 1985 and worked as an engineering consultant until 2001.

    Several of Rex’s publications have had substantial impact. In 1949 he and TVA colleagues Alvin Peterka and George Hickox received ASCE’s James Laurie Prize for their 1947 paper “Friction Coefficients in Large Tunnels.”1 Rex’s 1965 paper, coauthored with Don Harleman, “Withdrawal from Two-Layer Stratified Flow,”2 led to improvements in water intake design for thermal power plants on lakes and reservoirs. His 1970 paper, “Internal Hydraulics of Thermal Discharge Diffusers,”3 coauthored with Svein Vigander and Norm Brooks, substantially evolved the design of diffusers for wastewater effluents. And the chapter that Rex and Bechtel colleague Jack Cassidy wrote, “Spillways for High Dams,” for Developments in Hydraulic Engineering (Vol. 2, Taylor and Francis Group, 1984), is still widely consulted.4

    Over the years, Rex’s concern for the advancement of hydraulic engineering led him to take on national and international leadership roles. He was vice president of the International Association for Hydro-Environment Engineering and Research (IAHR; 1984–87) and chaired several IAHR committees as well as committees of the American Society of Civil Engineers (ASCE).

    Rex received multiple honors for his contributions. He was elected to the NAE in 1978, and ASCE bestowed on him its Hunter Rouse Hydraulic Engineering Award (1984) and Hydraulic Structures Medal (1991). In the 1980s he became an honorary member and fellow of ASCE, and in 2009 an honorary member of IAHR. He was also recognized as a member of the Hall of Fame at OSU’s College of Engineering (1999) and a distinguished alumnus of Carnegie Mellon University (2007).

    He easily befriended and mentored other engineers, par­ ticularly younger ones, and collaborated with university-based hydraulics labs on contracted projects. In this context, he spent considerable time at the University of Iowa’s water engineering research institute, IIHR Hydroscience and Engineering, working on projects with his colleague and close friend Jack Kennedy.

    After his Bechtel retirement, Rex continued his cooperative research with IIHR as an independent consultant, focusing on fish passage projects in the Pacific Northwest. His dedication to the advancement of engineering students is exemplified by his generosity toward the John F. Kennedy Memorial Fellowship at IIHR, which supports senior year research ­projects of under-graduates investigating hydroscientific issues.

    Rex was a devoted family man and a woodsman at heart. He shared his love of hunting, fishing, and hiking with his chil- dren, first during their childhood years in Tennessee and, after their relocation to California, during salmon fishing expeditions to British Columbia with their close friend Duncan Hay.

    Rex is survived by his four children—Jack Elder, Carol Weatherspoon, Susan Mathis, and Will Elder—as well as eight grandchildren and seven great-grandchildren. He was preceded in death by his wife of 66 years, Janet Alger Elder, and his dear companion Mary Mackey.

    He will be remembered by his family, friends, and colleagues for his contributions to the betterment of society and his enduring legacy to hydraulic engineering and research.

    1 Proceedings of the American Society of Civil Engineers 73(4):451–70.
    2 ASCE Journal of the Hydraulics Division 91(4):43–58.
    3 ASCE Journal of the Hydraulics Division 96(2):509–27.
    4 The book was edited by Pavel Novak (1918–2018), who passed away the same day as Rex and was also a major figure in the engineering of hydraulic structures.

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